// bslmf_assert.h -*-C++-*-
#ifndef INCLUDED_BSLMF_ASSERT
#define INCLUDED_BSLMF_ASSERT
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
//@PURPOSE: Provide a compile-time assertion facility.
//
//@CLASSES:
//
//@MACROS:
// BSLMF_ASSERT: compile-time assert macro
//
//@DESCRIPTION: This component defines a macro that will generate a
// compile-time error if its constant integral expression argument evaluates to
// false (i.e., a value of '0'). The 'BSLMF_ASSERT' macro is similar to the
// standard run-time 'assert' macro, except that its argument is evaluated at
// compile-time, it produces no executable code, and it can be used safely in
// header files.
//..
// BSLMF_ASSERT(sizeof(int) >= sizeof(char)); // OK
// BSLMF_ASSERT(sizeof(double) < sizeof(char)); // COMPILE ERROR!
//..
// The second line will result in a compile error with a message stating that
// the type 'BSLMF_COMPILE_TIME_ASSERTION_FAILURE' is incomplete, usually
// preceded by the file and line number where the macro was used. The
// following error message is typical of most compilers:
//..
// $ CC -g myfile.cpp
// "myfile.cpp", line 86: Error: The type
// "BSLMF_COMPILE_TIME_ASSERTION_FAILURE<0>" is incomplete.
// 1 Error(s) detected.
//..
// If the macro argument is true, the macro will generate an innocuous
// 'typedef' with a name that is the concatenation of the symbol
// 'bslmf::Assert', and the value of '__LINE__' (which will be the line number
// in the file where the macro was called). For example, the first line from
// the example above might result in the following statement:
//..
// typedef bslmf::AssertTest<1> bslmf_Assert_85;
//..
// Note that these generated typedefs are implementation details of the
// compile-time checking facility and are not intended to be used directly
// outside of this component.
//
// Attempting to invoke 'BSLMF_ASSERT' on a non-compile-time value will
// typically result in a compilation error.
//
// 'BSLMF_ASSERT' can be used at namespace, class, and function scope to assert
// compile-time conditions. !WARNING:! a compiler bug on certain platforms
// produces an error when the 'BSLMF_ASSERT' macro is used more than once on
// the *same* line in class scope.
//..
// +---------------------------------------------
// | // mytype.h
// | #ifndef INCLUDED_BSLMF_ASSERT
// | #include <bslmf_assert.h>
// | #endif
// |
// | class MyType {
// | BSLMF_ASSERT(sizeof(int) >= sizeof(char)); // OK
// | BSLMF_ASSERT(sizeof(int) >= sizeof(char)); // OK
// | BSLMF_ASSERT(1 == 1); // OK
// | BSLMF_ASSERT(1 == 1); BSLMF_ASSERT(1 == 1); // SAME LINE - MIGHT
// | // CAUSE ERROR!
// |
// | int d_data;
// | ...
// | void foo();
// | ...
// | };
//
// +---------------------------------------------
// | // mytype.cpp
// | #include <mytype.h>
// | #include <bslmf_assert.h>
// |
// | BSLMF_ASSERT(sizeof(int) >= sizeof(char));
// |
// | void MyType::foo()
// | {
// | BSLMF_ASSERT(sizeof(int) >= sizeof(char));
// | ...
// | }
//..
#include <bslscm_version.h>
#include <bsla_maybeunused.h>
#include <bsls_compilerfeatures.h>
#include <bsls_platform.h>
#ifdef BSLS_COMPILERFEATURES_SUPPORT_STATIC_ASSERT
#define BSLMF_ASSERT(BSLMF_CONSTANT_EXPRESSION) \
static_assert((BSLMF_CONSTANT_EXPRESSION), #BSLMF_CONSTANT_EXPRESSION)
#else
namespace BloombergLP {
// ==============
// Support macros
// ==============
#define BSLMF_ASSERT_CAT(X, Y) BSLMF_ASSERT_CAT_IMP1(X, Y)
#define BSLMF_ASSERT_CAT_IMP1(X, Y) BSLMF_ASSERT_CAT_IMP2(X, Y)
#define BSLMF_ASSERT_CAT_IMP2(X, Y) X##Y
// =============
// Support types
// =============
#if defined(BSLS_PLATFORM_CMP_SUN) && BSLS_PLATFORM_CMP_VERSION < 0x5130
// Using a different implementation on Sun; see BSLMF_ASSERT for details.
namespace bslmf {
struct Assert_TrueType {
typedef int BSLMF_COMPILE_TIME_ASSERTION_FAILURE;
};
struct Assert_FalseType {
};
template <bool COND>
struct Assert_If : Assert_TrueType {
};
template <>
struct Assert_If<false> : Assert_FalseType {
};
} // close package namespace
#else
template <bool IS_VALID>
struct BSLMF_COMPILE_TIME_ASSERTION_FAILURE;
// Declared but not defined. If assert macro references this type, then
// compilation will fail (assert failure).
template <>
struct BSLMF_COMPILE_TIME_ASSERTION_FAILURE<true> {
// Specialization for value 1 (true). Referencing this specialization will
// allow compilation to succeed (assert succeeded).
enum { VALUE = 1 };
};
namespace bslmf {
template <bool IS_VALID>
struct AssertTest {
// Instantiating this type involves instantiating its template parameter.
// This dummy type is just used to force instantiation of a meta-function
// used as its argument.
};
} // close package namespace
#endif
// ==================
// macro BSLMF_ASSERT
// ==================
#if defined(BSLS_PLATFORM_CMP_SUN) && BSLS_PLATFORM_CMP_VERSION < 0x5130
// The usual definition of the 'BSLMF_ASSERT' macro doesn't work with SunCC
// (version 10 and below) inside template classes. Note that Sun CC has a
// quite non-conformant (read 'broken') template instantiation mechanism. See
// DRQS 29636421 for an example of code Sun CC didn't compile correctly with
// the usual definition of 'BSLMF_ASSERT'. Below is the definition that works
// more reliably. This definition is not well-formed, it just happens to work
// with SunCC. So don't use it with other compilers.
#define BSLMF_ASSERT(expr) \
struct BSLMF_ASSERT_CAT(bslmf_Assert_, __LINE__) \
: ::BloombergLP::bslmf::Assert_If<!!(int)(expr)> \
{ \
BSLMF_COMPILE_TIME_ASSERTION_FAILURE * dummy; \
}; \
\
enum { BSLMF_ASSERT_CAT(bslmf_Assert_Check_, __LINE__) \
= sizeof(BSLMF_ASSERT_CAT(bslmf_Assert_, __LINE__)) } \
#else
#define BSLMF_ASSERT(expr) \
BSLA_MAYBE_UNUSED typedef BloombergLP::bslmf::AssertTest< \
sizeof(BloombergLP::BSLMF_COMPILE_TIME_ASSERTION_FAILURE<!!(expr)>)> \
BSLMF_ASSERT_CAT(bslmf_Assert_, __LINE__)
#endif
} // close enterprise namespace
#endif // BSLS_COMPILERFEATURES_SUPPORT_STATIC_ASSERT
#endif
// ----------------------------------------------------------------------------
// Copyright 2013 Bloomberg Finance L.P.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ----------------------------- END-OF-FILE ----------------------------------